Improving orientation with respect to gravity enhances balance and gait recovery after stroke: DOBRAS cohort.

BACKGROUND: Lateropulsion is a deficit in body orientation with respect to gravity, frequent after stroke. Although it is a primary factor affecting mobility, the impact of its attenuation on balance and gait recovery has never been investigated. Moreover, most studies on the lateropulsion time-course focus on severe forms suspected to have a poor recovery, which is not proven. OBJECTIVES: To investigate lateropulsion attenuation and test 2 hypotheses: 1) lateropulsion attenuation greatly contributes to balance and gait recovery and 2) severe forms of lateropulsion recover slower than moderate forms. METHODS: This longitudinal study involved individuals included in the Determinants of Balance Recovery After Stroke (DOBRAS) cohort, after a first-ever hemispheric stroke, with data collected on day 30 (D30), D60 and D90 post-stroke. Body orientation with respect to gravity was assessed using the Scale for Contraversive Pushing (both scores and severity grouping), in parallel with balance (Postural Assessment Scale for Stroke) and gait (modified Fugl-Meyer Gait Assessment). RESULTS: Among the 106 eligible individuals (mean age 66.5 [SD 9.7] years), on D30, 43 (41%) were considered upright and 63 (59%) showed lateropulsion: 30 (28%) moderate and 33 (31%) severe. Most individuals with lateropulsion (73%) improved their body orientation, progressing from severe to moderate lateropulsion, or becoming upright. However, half were still not upright on D90. The improvement in body orientation had a large impact on mobility, especially in individuals with severe lateropulsion, in whom it explained about 50% of balance and gait recovery between D30 and D60, then 20% (D60-D90). For moderate lateropulsion, its attenuation explained about 20% of balance and gait recovery until D90. Lateropulsion attenuation was not slower in individuals with severe forms. CONCLUSIONS: Lateropulsion attenuation enhances balance and gait recovery in individuals after stroke suggesting that specific rehabilitation of body orientation with respect to gravity might help to recover mobility. REGISTRATION: NCT03203109.

Pilot study assessing the impact of intrathecal baclofen administration mode on sleep-related respiratory parameters.

OBJECTIVE: To assess the impact of intrathecal baclofen (ITB) mode of administration on sleep and sleep-related breathing events in severely disabled patients with severe spasticity. DESIGN: Open prospective trial. SETTING: Physical medicine and rehabilitation department. PARTICIPANTS: Patients (N=11) treated with ITB pump for severe spasticity. INTERVENTION: Assessment of patients' sleep before and after ITB pump implantation, and comparison of polysomnography results after continuous or bolus mode of administration of ITB. MAIN OUTCOME MEASURES: Polysomnography and sleep-related breathing events. RESULTS: ITB reduced periodic limb movements and increased the respiratory disturbance index (RDI) and central apneas in our population of patients. This study showed that ITB mode of administration may affect sleep-disordered breathing. Indeed, we observed a significant increase of respiratory events in the bolus condition (RDI and central apneas). In contrast, continuous infusion did not induce a significant modification of sleep-disordered breathing. When a sleep apnea syndrome was preexisting, it was generally severely worsened by the bolus mode of administration. CONCLUSIONS: These results indicate that sleep function and sleep-related respiratory events should be assessed before ITB pump implantation. It is probably better to use a continuous mode of infusion if patients have preexisting sleep-disordered breathing.

Humans use internal models to construct and update a sense of verticality.

Internal models serve sensory processing, sensorimotor integration and motor control. They could be a way to construct and update a sense of verticality, by combining vestibular and somatosensory graviception. We tested this hypothesis by investigating self-orientation relative to gravity in 39 normal subjects and in subjects with various somatosensory losses showing either a complete deafferentation of trunk and lower limbs (14 paraplegic patients after complete traumatic spinal cord injury) or a gradient in the degree of a hemibody sensory loss (23 hemiplegic patients after stroke). We asked subjects to estimate, in the dark, the direction of the Earth vertical in two postural conditions-upright and at lateral whole body tilt. For upright conditions, verticality estimates were not different from the direction of the Earth vertical in normal (0.24° ± 1; P = 0.42) and paraplegic subjects (0.87° ± 0.9; P = 0.14). The within-subject variability was much greater in hemiplegic than in normal subjects (2.05° ± 1.15 versus 1.06° ± 0.4; P < 0.01) and greater in paraplegic than in normal subjects (1.13° ± 0.4 versus 0.72° ± 0.4; P < 0.01). These findings indicate that, even if vestibular graviception is intact, somaesthetic graviception contributes to the sense of verticality, leading to a more robust judgement about the direction of verticality when vestibular and somaesthetic graviception yield congruent information. As expected, when normal subjects were tilted, their verticality estimates were biased in the direction of the body tilt (5.55° ± 3.9). This normal modulation of verticality perception (Aubert effect), was preserved in hemiplegics on the side of the normoaesthetic hemibody (ipsilesional) (6.09° ± 6.3), and abolished both in paraplegics (1.06° ± 2.5) and in hemiplegics (0.04° ± 6.7) on the side of hypoaesthetic hemibody (contralesional). This incongruence did not exist in deafferented paraplegics who exclusively used vestibular graviception with a similar efficacy no matter what the lateral body position. The Aubert effect was not an on-off phenomenon since the degree of hemiplegics' somatosensory loss correlated with the modulation of verticality perception when they were tilted to the side of hypoaesthetic hemibody (r = -0.55; P < 0.01). The analysis of anatomical correlates showed that the Aubert effect required the integrity of the posterolateral thalamus. This study reveals the existence of a synthesis of vestibular and somaesthetic graviception for which the posterolateral thalamus plays a major role. This corresponds to a primary property of internal models and yields the neural bases of the Aubert effect. We conclude that humans construct and update internal models of verticality in which somatosensory information plays an important role.

Early post-stroke period: A privileged time for sensory re-weighting?

BACKGROUND: Shortly after stroke, patients exhibit excessive sensitivity to visual, proprioceptive and vestibular perturbations regarding balance control. OBJECTIVE: To evaluate the stability of this perceptual behaviour after stroke and test the relationships between sensory sensitivity and balance. METHODS: Thirty subjects following a hemispheric stroke (mean age 54.7 (standard deviation (SD) 10.6 years), 21 men, right hemisphere lesion = 13) and 30 control subjects (mean age 52.0 (SD 12.0), 14 men). Sensitivity to sensory perturbations was evaluated using the displacement of the centre of pressure during tendon vibration (proprioception score), optokinetic (visual score) and galvanic perturbations (vestibular score) while standing on a force-platform a mean of 2 months after stroke, and 1 month later. Balance and independence were evaluated using the Berg Balance Scale (BBS), Timed Up and Go test (TUG) and Barthel Index (BI). RESULTS: Global sensitivity to perturbations decreased (p = 0.001). Patients remained more sensitive to visual perturbation than did controls (p = 0.033). The Vestibular Score was correlated with BBS (Rs = -0.576, p = 0.006), TUG (Rs = 0.408, p = 0.045), BI (Rs = -0.481, p = 0.016); the Visual Score was correlated with BBS (Rs = -0.500, p = 0.019), TUG (Rs = 0.401, p = 0.049). CONCLUSION: The initial months following stroke appear to be a period of individual perceptual motor adaptation. Sensory re-weighting is likely to be a major component of that process.